Laser systems for performing work operations on sheet material are known. For example, U.S. Pat. No. 5,268,554, the disclosure of which is incorporated herein by reference, describes a laser system which includes a scanning mirror positioned above a support surface for directing the focal point of a laser beam onto sheet material supported on the surface. A flexible drive system is provided for three dimensional operation of the scanning mirror and, accordingly, full three dimensional manipulation of the focal point of the beam with respect to the sheet material. The drive system is operably connected to a controller, such as computerized numerical controller (cnc) or a programmable logic controller (plc), to control the orientation of the scanning mirror and direct the focal point of the beam onto the work material along a pre-programmed path.
Devices of this type may be used to perform a number of materials processing techniques including drilling, cutting, marking, curing and engraving. In particular, scanning laser systems are useful for controlled cutting of limp sheet materials, such as fabric, according to a pre-programmed pattern defined by a plurality of X-Y coordinates.
There are, however, a number of disadvantages associated with the use of such systems, including the inability to precisely position the focal point of the laser beam at a particular X-Y coordinate on the sheet material. In this connection, it should be understood that the laser system is capable, within certain acceptable tolerances, of accurately directing the focal point of the beam to a particular coordinate position on the sheet material. The positioning inaccuracies derive from the topography of the sheet material and/or the support surface. That is, if the work material does not lie flat against the surface and/or the surface is not precisely planar, the focal point of the beam will not fall at the intended coordinate position on the sheet material.
Beam attenuation is a second disadvantage associated with the use of laser systems for materials processing. As explained more fully below, the optical components of a laser system used for materials processing are typically contained within a shrouded enclosure to protect the mirrors and other associated components from damage and to protect the operator of the system from dangerous exposure to the direct laser beam, as well as stray reflections of the beam. Unfortunately, during processing the enclosure quickly becomes clouded with the gases and particulates produced during the work operation. Since the laser beam is typically reflected several times within the enclosure between a number of mirrors and the scanning mirror is positioned well above the support surface (in some systems up to about 100 inches above the surface), significant attenuation can result by the time the beam finally reaches the support surface, if the gases and particulates are not continuously removed from the enclosure. Moreover, the mirrors themselves can quickly become coated with airborne particulates, resulting in improper direction and focusing of the beam by the laser's optical system. This problem is of particular concern in those systems which include a mirror having an upwardly facing reflective surface.
Accordingly, it is an object of the present invention to provide a materials processing apparatus having a precisely planar support surface for supporting sheet material during a work operation.
It is a further object of the invention to provide a work table providing such a support surface.
It is a still further object of the invention to provide such a table wherein the sheet material is held flat against the support surface during the work operation.
It is yet another object of the invention to provide a materials processing apparatus including a laser system, wherein an enclosure containing the laser system's optics is kept free of gases and particulates during the work operation.